Both enzymes are present in the liver tissue. Their activity in serum is very low when the liver cells are intact. Leakages of these cenzymes occurs in case of hepatocellular injury which affect the permeability of the liver cell wall and allows enzymes to escape.
Please note that SGOT and SGPT are also present in the renal tubular epithelium and heart muscles
Non-alcholic fatty liver disease (NAFLD) include wide spectrum...Fatty liver disease alone does not increase liver enzymes,while non-alcholic steatohepatitis (NASH) could be presented by mild increase in liver enzymes ..This hepatitis will be relieved by the appropriate treatment
There is a modest increase in blood levels of both enzymes without any clinical relevance produced by increased cell permealibility of their cell liver membranes